Playing with pencils is always fun, either with stamps or just sketching stuff. I use Prismacolour Premium pencils (bought them at a sweet price on ebay) because they are creamy and blend well. Besides the pencils, the paper also makes a huge difference on the final results, so I always use Winsor and Newton's Bristol paper pad because it is really smooth, ideal for stamping, sketching, whatever.
When I color stamped images, I always use a black ink (to stamp) that won't bleed , for instance Versafine, and when I'm finished I like to outline the image with a dark marker.
Paper stumps are really usefull (in various sizes) in combination with an odourless spirit (I use Sansodor) because it makes blending easier, although you can have beautiful results without them, it's just a matter of taste.